The present invention generally relates to an access port for a house vacuum system used in a semiconductor fabrication facility and more particularly, relates to an access port for a house vacuum system that is equipped with a removable trap for preventing the access port from being plugged up by the vacuumed debris.
In the recent development of semiconductor fabrication technology, the continuous miniaturization in device fabricated demands more stringent requirements in the fabrication environment and contamination control. When the feature size was in the 2 xcexcm range, a cleanliness class of 100-1000 (which means the number of particles at sizes larger than 0.5 xcexcm per cubic foot) was sufficient. However, when the feature size is reduced to 0.25 xcexcm, a cleanliness class of 0.1 is required. It has been recognized that an inert mini-environment may be the only solution to future fabrication technologies when the device size is reduced further. In order to eliminate micro-contamination and to reduce native oxide growth on silicon surfaces, the wafer processing and the loading/unloading procedures of a process tool must be enclosed in an extremely high cleanliness mini-environment that is constantly flush with ultrapure nitrogen that contains no oxygen and moisture.
Different approaches in modern cleanroom design have been pursued in recent years with the advent of the ULSI technology. One is the utilization of a tunnel concept in which a corridor separates the process area from the service area in order to achieve a higher level of air cleanliness. Under the concept, the majority of equipment maintenance functions are conducted in low-classified service areas, while the wafers are handled and processed in more costly high-classified process tunnels. For instance, in a process for 16M and 64M DRAM products, the requirement of contamination control in a process environment is so stringent that the control of the enclosure of the process environment for each process tool must be considered. This stringent requirement creates a new mini-environment concept which is shown in FIG. 1A. Within the enclosure of the mini-environment of a process tool 10, an extremely high cleanliness class of 0.1 (which means the number of particles at sizes larger than 0.1 xcexcm per cubic foot) is maintained, in contrast to a cleanliness class of 1000 for the overall production cleanroom 12. In order to maintain the high cleanliness class inside the process tool 10, the loading and unloading sections 14 of the process tool must be handled automatically by an input/output device such as a SMIF (standard mechanical interfaces) apparatus. A cassette or wafer can be transported into the process tool 10 by SMIF pod 18 situated on top of the SMIF apparatus 20.
Also provided in the cleanroom 12 is a house vacuum system equipped with a vacuum access port 40 shown in FIGS. 1A-1C. The vacuum access port 40 is constructed by a vacuum conduit 42 and a cover assembly 44. The house vacuum system is provided with the vacuum access port 40 throughout a cleanroom, which is normally installed in the cleanroom floor such that a top surface of the cover assembly 44 is flush with the top surface 32 of the cleanroom floor. The purpose of the house vacuum system is to provide ready access to a factory vacuum source for cleaning of process tools or work areas. The vacuum conduit 42 is provided with an apertured plate 50 with a plurality of apertures 52 therein for filtering out or stopping large debris that are vacuumed into the conduit 42.
The cover assembly 44 for the vacuum access port 40 is shown in detail in FIG. 1B in a perspective view. The cover assembly 44 is normally provided with a recess 34 in a top surface 36 of the cover assembly 44. The recess 34 is further provided with a pin 38 for grasp by a pair of pincers during a preventive maintenance procedure. The cover assembly 44 is constructed by an upper portion 46 and a lower portion 48 that are both formed in an annular shape. The outside diameter of the lower portion 48 is only slightly smaller than the inside diameter of the conduit 42 such that a snug fit can be achieved for a vacuum-tight seal. FIG. 1C illustrates a cross-sectional view of the cover assembly 44 installed in the vacuum conduit 42.
The cover assembly 44 illustrated in FIGS. 1A-1C serves the purpose of sealing a vacuum outlet 40. However, whenever an operator needs to use the house vacuum by attaching a vacuum hose connector to the conduit 42, a pair of pincers or Allen wrench must be used to pick up the cover assembly 44 by the pin 38. This process must be repeated several times a day whenever a process chamber, or a work area needs to be cleaned. Moreover, the apertured plate 50 used in the vacuum conduit 42 for filtering out the debris from vacuuming can be easily plugged up such that the vacuum operation cannot be efficiently conducted. The plurality of apertures 52 in the apertured plate 50 can be easily jammed or blocked by the debris picked up during vacuuming. The removal of the debris from cavity 54 is inconvenient and awkward to access. Major improvements to the conventional vacuum conduit system and the vacuum access port are therefore needed for providing easy access to the house vacuum in a cleanroom.
It is therefore an object of the present invention to provide an access port for a house vacuum system that does not have the drawbacks or shortcomings of the conventional access ports.
It is another object of the present invention to provide an access port for a house vacuum system that is equipped with a removable trap for easier removal of vacuumed debris.
It is a further object of the present invention to provide an access port for a house vacuum system that includes a hinged cover for easier access.
It is another further object of the present invention to provide a portable vacuum access port for a house vacuum system wherein the access port protrudes above the floor panel.
It is still another object of the present invention to provide a vacuum access port for a house vacuum system equipped with a removable trap provided with a plurality of apertures both in a bottom and in a sidewall of the trap.
In accordance with the present invention, an access port for a house vacuum system that is equipped with a removable trap is disclosed.
In a preferred embodiment, an access port for a house vacuum system that is equipped with a removable trap is provided which includes a port body of elongated, cylindrical shape that has an open top and an apertured bottom in fluid communication with a vacuum source; a port cover pivotally connected to a floor panel by hinge means, the port cover has an outer dimension that is at least the outer dimension of the port body for sealingly engaging an upper rim of the port body when the port cover is in a closed position; a debris trap of elongated, cylindrical shape removably mounted inside the port body for collecting debris from a vacuuming operation and for allowing air to pass therethrough through a plurality of apertures provided in a sidewall and in a bottom plate of the debris trap; and a vacuum hose access means in the port cover for sealingly connecting a vacuum hose to a vacuum source.
In the access port for a house vacuum system, the vacuum hose access means may include a vacuum hose access port in the port cover and a cover for the vacuum hose access port pivotally connected to the port cover by a hinge means. The vacuum hose access port may be equipped with a downwardly projecting sidewall for frictionally engaging an outer peripheral surface of a vacuum hose when the cover for the access port is pivotally opened. The vacuum hose access means may further include a vacuum hose access port in the port cover and a cover for sealing the vacuum hose access port when the vacuum hose is not in use. The vacuum hose access port may be formed of an opening and an upwardly extending sidewall that has an inner peripheral surface for frictionally engaging a vacuum hose.
The present invention is further directed to an access port for a house vacuum system that is equipped with a removable trap which includes a port body of elongated, cylindrical shape that has an open top and an apertured bottom in fluid communication with a vacuum source; a port cover pivotally connected to a floor panel by hinge means, the port cover may have an outer dimension that is at least the outer dimension of the port body for sealingly engaging an upper rim of the port body when the port cover is in a closed position; a debris trap of elongated, cylindrical shape removably mounted inside the port body for collecting debris for a vacuuming operation and for allowing air to pass therethrough through a plurality of apertures provided in a sidewall and in a bottom plate of the debris trap; a vacuum hose access port in the port cover; and a cover for the vacuum hose access port pivotally connected to the port cover by a hinge means, the access port may be equipped with a downwardly projecting sidewall for frictionally engaging an outer peripheral surface of a vacuum hose when the cover for the access port is pivotally opened, the cover for the vacuum access port may have a diameter smaller than an outer dimension of the port cover.
In the access port for a house vacuum system that is equipped with a removable trap, the port body and the debris trap may have an annular cross-section, the outer dimension of the port cover may be a diameter of the port cover. The port body may further include a flange portion on an inner periphery of the port body for suspendedly supporting an upper flange of the debris trap. The debris trap may be equipped with an outwardly extending upper flange portion extended from an upper rim of the trap. The debris trap may be supported in a suspended manner spaced-apart from an inner periphery and the apertured bottom of the port body by a distance of at least 0.5 cm. The debris trap may further include a handle for ease of removal from the port body. The downwardly projecting sidewall on the vacuum hose access port may further include a stop mounted on an inner periphery of the sidewall to limit the downward travel of a vacuum hose.
The present invention is still further directed to an access port for a house vacuum system that is equipped with a removable trap which includes a port body of elongated, cylindrical shape that has an open top and an apertured bottom in fluid communication with a vacuum source; a port cover that is pivotally connected to a floor panel by hinge means, the port cover may have an outer dimension that is at least the outer dimension of the port body for sealingly engaging an upper rim of the port body when the port cover is in a closed position; a debris trap of elongated, cylindrical shape that is removably mounted inside the port body for collecting debris from a vacuuming operation and for allowing air to pass therethrough through a plurality of apertures provided in a sidewall and in a bottom plate of the debris trap; a vacuum hose access port in the port cover formed by an opening and an upwardly extending sidewall that has an inner peripheral surface for frictionally engaging a vacuum hose; and a cover for sealing the opening when the vacuum hose is not in use.